Harmonic relay.



K. B. MILLER. HARMONIO RELAY.

APPLICATION FILED JULY 17, 1909 Patented Nov. 11, 1913.

3 SHEETS-SHEET 1.

7 W W A K. 3. MILLER. HARMONIO RELAY.

AYPLIOATION FILED JULY 17, 1909.

Patented Nov. 11, 1913.

3 SHEETSSHEET 3.

Z m r W K UNITED s'rArEs PATENT OFFICE.

xnmrs'rnn i3. MILLER, or CHICAGO, ILLINOIS, ASSIGNOR T0 McMEEN & MILLER,or

CHICAGO, ILLINOIS, (SAMUEL e. McMEEN AND xnmrs'rnn 1B. MILLER) A.cornme- NERSHIP.

Specification of Letters Patent.

Application filed July-17, 1909.

HARMONIC RELAY.

Patented Nov. 11, 1913. Serial No. 508,096. 4

To all whom it may concern Be it known that LKEMPsTER B. MILLER, acitizen of the United States of America, and a resident of Chicago,county of Cook, and State of Illinois, have invented a new and usefulImprovement in Harmonic Relays, of which the following isaspecification.

My invention relates in general to apparatus and systems foraccomplishing the selective operation among a plurality of devicesconnected with a single circuit or circuits, and in particular itrelates to selective signaling on multi-party telephone lines. Thegeneral method which I employ to accomplish the selective operationamong the several devices associated with a circuit or the severalstations on a telephone party line, is to employ differently tuned reedsfor each of the devices or stations associated with the circuit or line,each of these reeds being adapted to be set into vibrationelectro-magneticallyby a particular frequency of alternating orpulsating current flowing in the circuit or line to which the devices orstations are attached. My invention therefore comes within thescope ofthat class of systems, for the selective operation of devices, which hasbeen termed harmonic in distinguishment from those classes whichaccomplish selection by step-by-step.movements,

or by changes in current strength or polarity, orby other means.

All of the successful systems of harmonic selection that have been usedin telephony have employed electromagnets having tunedreed armaturescarrying tappers which, when thrown into vibration, serve to strikedirectly against the gong orgongs to produce the desired sound. Suchsystems, wherein the gongs are struck by the direct action of the tunedreed, have been subject to certain defects which, while not suiticientlygreat to prevent their wide adoption,

able the bells to be successfully rung. In I have been present asobjectionable features and have served at least to place a ratherdistinct limitation on the number of devices that could be successfullyselectively operated over a single circuit. In one type of these directacting harmonic bells ithas been found necessary to resort to what iscalled the under-tuning system in order to enthis type it has been foundthat when the tapper strikes the gong, the rebound of the tapper fromthe gong tends to accelerate the rate of vibration of the tuned reed-ofwhich the tapper forms a part, and therefore to change the natural rateof vibration of the reed itself. If therefore the reed were tuned toaccurately correspond with the frequency of current that was to operateit, the striking of the rapper against the gong would tend to acceleratethe rate of vibration of the reed tongue, thus throwing it out of tuneand causing irregular and in sufiicient ringingl To secure an effectivering, it has been the custom in this class of harmonic bells to give thereed tongue a natural rate of vibration slightly below the correspondingcurrent. frequency, but yet suflicie'ntly close to it to enable thedesired current frequency to start the reed sufiiciently to strike thegong, after which the accelerating influence of the gong brought thenatural rate of the reed while striking the gong more nearly into unisonwith the operating striking harmonic bells the undertuning expedient hasnot been employed, the natural rate of vibration of the armature whennot striking the gong being made to correspond as accurately as possiblewith the frequency of the operating current, and in this case specialmeans have been adopted for preventing the gongs while being struck fromexerting any great tendency to throw the reedtongue out of tune. In allof these direct striking methods of harmonic selective ringing however,the requirement exists that a comparatively large amount of energy beemployed in the selecting current sent over the line, since this currentmust cause the bell armature that is actuated by it to strike the gongswith sufficient force to produce a loud, clear ringing of the bell. Asthe practice has been, and is, to employ a multiple or bridging relationof the bell coils with respect to the line, it follows that in the caseof a long line the nearer bells to the source of ringing current mustreceive a great excess of current in order that the more remote hellsmay receive enough. This necessary employment of currents very muchgreater in strength than is necessary to ring some of the bells, at oncesets up a condition which is favorable to cross ringing, that is, theringing of bells not corresponding to the current frequency employed, byovercoming their natural tendency to vibrate at one frequency and forcethem, by sheer strength, to vibrate at another frequency. This imposesthe re uirement that the frequencies employed di er widely one fromanother, and this in turn limits the number of stations that may beselectively operated.

Many attempts have been made to cause the harmonic device to act asarelay, and thus control the circuit of a responsive device, such as anordinary vibrating bell. In all devices of this kind that have beenproposed within my knowledge the tuned reed tongue has been caused, whenthrown into vibration, to strike against contact points separatelymounted. In some cases these contact points have been rigidly mountedand in other cases they have been yieldingly mounted, being usuallycarried .on springs or levers mounted independently of and separate fromthe reed tongue. In all these cases it has been found that the naturalrate of vibration of the reed tongue has been altered by the strikingagainst the contacts in the same manner that the rebound of the gongs inthe direct-striking harmonic bells altered the natural rate ofvibration. of their reed tongues. In addition to this, the closure ofthe circuit by such vibrating reeds has been intermittent, the circuitbeing closed and opened by each stroke of the reed.

My invention relates to harmonic devices which, when operated, serve toact as relays and thus perform their work indirectly through the controlof another circuit rather than directly, as where the tuned tonguestrikes directlyagainst the gongs. I avoid all of the difficulties thathave been found in practice in the prior types of harmonic responsivedevices by so arranging the reed tongue that the carrying out of itsfunction is not dependent upon its striking against any object duringits vibration. It carries a contact. closing device entirely withinitself, which device assumes one condition of circuit control while thereed tongue is at rest, and another condition of circuit control whenthe reed tongue is in vibration, the change'being dependent on the stateof rest or motion of the reed tongue and not upon its striking againstor making contact with any external thing.

I have illustrated my invention in the acspective view of the vibratingpart or reed tongue of my relay; F a is a sectional view of thisvibrating part or reed tongue; Fig. 5 is a sectional'view of one form ofcontact closing device carried by the reed tongue; Fig. 6 is anotherform of contactclosing device; Figs. 7 and 8 are other modifications ofthe contact-closing device; Fig. 9 shows the circuit arrangement of acomplete telephone party line employing my device; and Fig. 10 shows amodification of the telephone sub-stations of such a line; Fig. 11 showsanother arrangement of line equipment..

Referring now to Figs. 1 and 2, which illustrate the preferred form ofmy har monic relay, 1-l represent the two spools of an electroniagnet,the cores 2 of which are connected to a soft iron yoke bar 3 which alsoforms a convenient means for attachment of the relay as a whole to itsbase. In order that the device may be more readily adaptable foralternating current work, I provide a polarizing magnet 4, which ispreferably a permanently magnetized L-shapcd bar of steel attached tothe yoke piece 3 and extending to a point in proximity to the rigidpoint of support of the armature. Over the polar ends of the cores 2 Iforce screwthreadcd metal collars 5, which at once form heads for thecoil windings and an adjustable means of support for the arn'iaturecarrying yoke 6. This yoke 6 is held. rigidly on the collars 5 andtherefore on the cores 2 by means of the two pairs of screw-threadednuts 7-7 which engage the screw threads on the parts 5 and clamp thepart 6 between them. In this way the entire yoke 6 may be movedlongitudinally with respect to the cores, so that the armature 8 carriedby the yoke may be moved closer to or farther from the pole pieces. Thetwo downwardly projecting ears 6, of the yoke 6 areslotted to receivethe screw-threaded shanks from the block 9 which supports the armature.This block 9 is held in place in the yoke 6 by the nuts 9.

The vibrating reed as a whole is shown in perspective view in Fig. 3 andin sectional viewin Fig. 4. The reed spring 10 is clamped directlyagainst the supporting block 9 as indicated, and for this purpose thisblock may be either split or a separate block 9 may be used, this beingheld on the opposite side of the spring 10 from the block 9 by means ofrivets or screws being as indicated. The armature r0 er, 8, in the formIffhave illustrated, is two L-shaped pieces of soft iron, these beingriveted together so as to include the free end of the spring 10 betweenthem, and so also as to include the armature rod 12 which carries at itsouter end the circuit controlling device 13.

I preferably make the armature rod 12- hollow so that it may carrywithin it, and insulated from it, a wire 11 forming the return side ofthe circuit leading to the circuitcontrolling device 13. The rod or tube12 thus forms one side of the circuit leading to the circuit-controllingdevice, and the wire 14: Within this tube the return side of thiscircuit. In order that the wire 14: .may be carried directly from theend of the tube 12 without making contact with other metallic bodies,the reed spring 10 is offset from the line of the tube 12, as mostclearly shown in Fig. 1. The wire 14 may thus pass in a direct linethrough a hole in the block 9, in which hole I preferably place aninsulating bushing 15 to prevent electrical contact between the wire andthe block.

The Wire 14 I preferably make of phosphor bronze, or other resilientmetal so that it may partake of the slight bending to whichit issubjected when the armature is vibrated. An insulating tube 16 surroundsthis wire throughout the entire length of the tube 12 and thus insulatesit from that tube.

A preferred form of circuit-controlling device to be carried upon theouter end of the armature rod is illustrated in Fig. 5. This figureshows the upper end of the hollow rod 12 to have been expanded to form achamber 17 of sufficient diameter to receive the current-controllingunit. The circuit-controlling device proper, as indicated in Fig. 5, is

comprised in the thimble 18 and the parts contained therein, these partsbeing removable from the chamber 17 bodily. The cap 18 is composed ofiron, or it may be of electrolytic copper or aluminum. The downwardprojection 18 from. the center of. the inner surface of the cap 18 formson electrode of the circuit-controlling device. This projection 18 maybe of the same metal and integral with the body of the cap 18, or it maybe in the form of a rivet as indicated in dotted lines in Fig. 5, inwhich case it might be of a different metal, such as platinum. The otherelectrode of the device is the metallic cup 20 which may be of iron,electrolytic copper, aluminum or platinum. This inner cup 20 forms areceptacle for a small drop' 21 of some conducting fluid such asmercury. The cup 20 is electrically insulated from the cap 18 by aninsulating bushing 19, these three parts,the inner cup, the bushing andthe cap, being forced together under considerable pressure so as to, asnearly as posormed of sible, hermetically seal the mercury contain ingchamber. The sealing of this chamber is further provided for bycoatingthe outer cylindrical surface of the inner cup 20 and the inner surfaceof the cap 18 with suitable cement before pressing these parts-togetherand by afterward filling the vacant space 22 between the inner and outercups with a f cement which when set will form a nonporous m'assresembling enamel. To the bottom of the cup, 20 is soldered or otherwise1 secured the enlarged and flattened end of the conducting wire 1%which, as before stated, extends through the insulating bushing 16within the tube 12 and forms the return circuit for the circuitcontrolling device.

The entire circuit-controlling device is held tightly in place withinthe chamber 17, either by the tightness of the fit in the constructionillustrated or by providing screw threads on the inner surface of thechamber 17 and the outer surface of the cup 18,

\Vhen the harmonic relay is at rest, the drop of mercury or other fluidoccupies the position shown and is therefore in contact only with thecup 20. As soon, however, as the reed tongue is thrown into vibration bythe rhythmical action of an operating current vith which it is in tune,this drop of mercury is thrown. partly by centrifugal action and partlyby the general churning up effect, to the top of the chamber in whichposition it makes contact also with the projection 18' from the cap 18,thus completing the circuit between the armature rod 12 and the inner'con'dnctor 14. It will hold this circuit closed as long as the reedtongue continues to vibrate, and upon the cessation of vibration themercury will drop back into the position shown, thus breaking thecircuit.

Anot-her'form of circuit-controlling device is shown in Fig. 6. In thisthe mercury 22 is contained within the metallic cup Q3, which is flangedat its top. This cup is seated within an insulating bushing .24, whichin turn rests within the enlargement or chamber 17 of the tube 12. Theupper electrode is in this case a metal disk 25 separated and insulatedfrom the cup 23 by the bushing 26. These parts are firmly bound togetherby screwing home .the cap 27, an internal screw thread in which, engagesan external screw thread on the enlarged end of the tube 12. In order toprovide as completely as possible for the hermetic sealing of themercury chamber,-the insulating bushing or washer 26 is of a non-porousnature and is coated with a suitable cement before it is placed betweenthe flange of the cup 23 and the disk 25, and the space 28 surroundingthese parts is also filled with an enamel cement with the same end inview.

In some cases I may make the insulating bushing 19 of Fig. 5 or 26 ofFig. 6 of glass and fuse it by heat directly to the electrodes untilafter it has cooled off, then supplied through a small opening which isafterward properly sealed. 1

In Fig. 7 I have shown still another form of-circuit-controlling device.In this the mercury chamber 28 is all glass, through the walls of whichtwo electrodes 29 and 30, preferably of platinum, project, beingpreferably sealed in. This entire capsule so formed may be securedwithin a suitable receptacle 31 carried by the armature rod 12, as byembodying it in some cement or wax which when set will presentsufficient rigidity. Any tendency which the mercury may have to oxidizemay of course be prevented by excluding the air from the capsule, andthe forming of the capsule of glass, as indicated in Fig. 7, isadvantageous from that standpoint.

So far in this specification I have referred to mercury or some otherconducting fluid as the substance to be employed within the capsule forthe purpose of completing the circuit bet-ween the two electrodes. 'Asan alternative, very small particles of solid conducting material, suchas carbon, or small metallic particles, may be used. These particles maybe gold-plated to insure better contact and freedom from oxidation. In-

stead of employing a multitude of such solid conducting particles, I mayemploy a single metallic ball, preferably gold plated, as is shown inFig. 8. Experiment has proven -that such a ball will, when the armatureis thrown into vibration, rise within its chamber until it makes contactwith the upper elect-rode. The employment of solid rather than fluidcircuit-closing materials is advantageous in that the problem ofhermetically sealing the chamber does not enter. The use of mercuryhowever affords a surer means of closing the'circuit, there being nodifliculty in this case, due to improper C011? tact. An efficientcircuit closer is produced by amalgamating the ball of Fig. 8 withmercury, thus causing it to present at all times a surface wet withmercury.

The complete reed tongues carrying the circuit-controlling device may betuned to respond to any frequency of operating current-by purelymechanical means. Itis obvious that the distance from the centers ofgravity of the various moving parts of the vibrating structures and theeffective pivotal point thereof will enter into the natural rate ofvibration of the reed tongue as will also the weight of the severalparts and the strength and length of-the reed spring. In order to varythe natural rate of vibration of any reed tongue, and to adjust it tothe desired rate, I provide a weight 32 which is slidable upon the rod12 and may be fixed harmonic bells, the range of frequency that it hasbeen found feasible-to employ has been from about 16 cycles .per secondas the lower limit and 66 cycles per second as the higher limit. Sincemy device is not limited by any requirement as to the sounding of thegong, I may employ a much wider range than this, and the range which Iprefer is limited by about 16 cycles per second as the lower limit and200 cycles per second as the higher limit. \Vithin this range I mayemploy a great number of frequencies with corresnondingly tuned reedswithout danger of interference. I preferably make the mass of themercury drop, or of whatever movable conductor I employ, very small incomparison with the mass of the moving parts of the vibrating reed, andalso I preferably make the movement of this mass, toward or from theeffective pivotal point of the reed tongue, as small as possibleconsistent with surety in making andbreakingthe circuit, in order thatthe moment of inertia of the entire reed tongue about its effectivepivotal point may be altered to as small a degree as possible so thatthe change in center of gravity due to the slight displacement of thecircuitclosing material in operation will not materially alter thenatural rate of vibration of the reed tongue.

I have illustrated certain circuit arrangements in which my harmonicrelay may be found useful in Fig. 9, this being a representation of ametallic circuit telephone line containing three stations, together withthe terminal for this line in the central oflice, and the ringingapparatus at the central office. The line wires 40 and 41 extend fromthe spring jack 42 at the central office to the several telephonestations. At each of these stations there is shown, by the usualdiagrammatic symbols, the telephone receiver and transmitter adapted tobe bridged across the metallic circuit when the receiver is removed fromthe'switchhook for use, this arrangement being that commonly employed inthe so-called common battery systems. I have shown at the central officeone of the common arrangements for receiving signals from the stations.I have shown at each station one of my harmonic relays as 43 bridgedacross the line wires. Each of these relays when operated serves to.close the contact 45, thus completing the circuit through a polarizedbell 46'.

At the central office I have shown three generators 46, 47 and 48,together wit-h the usual ringing keys for associating them with a cordcircuit and the usual plug 49 for con necting thecord circuit with thesprin jack of any line.- These generators are a apted circuit b togenerate alternating or pulsating current, each of a particularfrequency, 1 the frequencies corresponding respectively to the naturalratesof vibration of the reed tongues of the relays 43, 43' and 43". If,there ore, the generator 46 is connected across the cord thecorresponding ringing key, the current from that generator will passover the metallic circuit and through the bridges at all of the stationsin parallel. Only one of the relays, 43 for instance, will be operated,since that alone will have a reed tongue tuned to that particularfrequency. The operation of this relay will close the contact 45 andthus cause the polarized bell 46' to receive current from the line andto be actuated thereby, these bells being adapted to respond to the samecurrent that actua'tes the relay.

The telephone transmitters of the circuit of Fig. 9 are supposed toderive their cur'- rent from a central oflice battery in accordance withthe usual common battery method of operation. Where desired however, abattery 49, local to each station, may serve to supply the transmittercurrent, and also may serve to ring a vibrating bell. 49 through therelay contact, this arrangement being indicated in Fig. 10.

A modification of the system of Fig. 9 is shown in Fig. 11. In thismodification all of the polarized bells 50 are alike, and are adapted tobe rung by a generator 50, of which three are shown at the centralofiice. In conjunction with each of the three ringing keys is shown agenerator 46, 47, 48, respectively, producing current adapted to actuatethe harmonic relays 46", 47", 48" respectively. Upon the actuation ofany ringing key, twogenerators are placed upon the line in multiple, andtwo superimposed periodically varying currents pass over the line, oneof which actuatcs the relay to close its contact and the other of whichactuatcs the signal bell'through the relay contact. This is a desirablearrangement for the rea-.

- to the closing of circuits for the purpose of ringing telephone bells.It is adapted for use in telegraphy and in railway signaling systems,and in fact in any of the electrical arts wherever it is desired that acircuit shall be controlled or a device operated upon the sending of oneparticular frequency of current to the exclusion of all others.

It is obvious that change in the position of the mercury, or othermovable circuit closin member carried by the reed, need not depenmovement ,to' control the circuit. It is obvious that the contacts maybe so arranged that any considerable vibration of the reed will soagitate the mercury or other fluid as to cause it to merely change itsshape and thus close or open the break in the controlled circuit. I 'donot wish therefore to be limited in this respect to harmonic relayswhich depend on centrifugal action to throw the mercury or other circuitclosing member into its alternate position, but I desire to include anyarrangement by which the circuit-controlling member which is carried onthe reed will assume and continuously hold one condition of circuitcontrol while the reed is vibrating and another condition of circuitcontrol while the reed is at rest.

It is obvious that the relays may have their contacts so arranged as tonormally hold the circuit closed and to hold it continuously open whenthe reed is in vibration, such modification from the arrangementillustrated being well within the skill of the art in view of thedisclosures herein made. It is also obvious that many changes may bemade in the construction of the relay. Thus, instead of employing thetype of magnetic circuit where the cores of the two operating coils areside by side and parallel, I may employ any of the other well-knownmagnetic circuits such, for instance, as that employed in the harmonicbell shown in patent to W. W. Dean No. 779,533, wherein the cores of theoperating coils are placed in line with each other and present theirpoles to the opposite sides of what may be termed a straight-linearmature.

. Having thus described my invention, what I claim as new and desire tosecure by United States Letters Patent is:

1. A relay; a vibratory member therefor; circuit-controlling contactsvibrating with said vibratory member, adapted to be held continuously inone condition of circuit control while said member is in vibration andcontinuously in another condition of circuit control while said memberis at rest.

2. A'relay; a vibratory member therefor; circuit-closing contactsvibrating with said vibratory member, said contacts being held closedwhile said member is in vibration and open while said member is at rest.

3. In a relay, a vibrating reed; a pair of contacts carried by saidreed, said contacts being electrically connected while said reed isvibrating and disconnected when said reed is at rest-.-

4. In a harmonic relay, a tuned reed armature therefor; a pair ofcontacts carried by said tuned reed armature, said contacts beinginsulated from each other while said turned reed armature is at rest andcontinu upon centrifugal action for its,

' ture therefor; a pair of contacts controlled by said tuned reedarmature, said contacts being insulated from each other while saidtunedreed armature is at rest and continuously electrically connectedwhile said tuned reed armature is in vibration.

6. In a relay, a reed adapted to be electromagnetically vibrated; acircuit-controlling device carried on said reed, saidcircuit-controlling device being adapted to assume one condition ofcircuit control while said reed is at rest and another while said reedis being vibrated.

7. In a relay, a vibrating armature; an electrical switch carried bysaid armature; and centrifugally controlled means for closing saidelectrical switch.

8. In a relay, a vibrating armature; a contrifugally controlled electricswitch carried by said armature and operated by reason of the vibratorymovement thereof.

9. In a relay, a vibrating armature; a centrifugally movable conductingelement carried by said armature; and other conducting elements fixedupon said armature and moving therewith and with which said movableelement is adapted to make contact.

10. In a relay, an electromagnetically controlled vibrating part; a pairof contact members upon said vibrating part and const-itutin electricalterminals; a movable conducting element carried by said moving 3 partand adapted to connect said two contact members.

11. In a relay, an electromagnetically controlled vibrating part; acentrifugally controlled movable member upon said vibrating partandcarried thereby; and fixed electrical contact members carried upon saidvibrating part with which said centrifugally movable part may makecontact.

12. In a relay, a vibratory member; .a 4 switch carried by saidvibratory member; means for opening said switch when said vibratorymember is at rest and for continuously closing said switch when saidvibratory member is in motion.

13. A relay; a vibratory member therefor; circuit-controlling terminalscarried on said vibratory member; a readily movable member also carriedby said vibratory memberand adapted to connect said terminals While saidvibratory member is in vibration.

Signed by me at Chicago, county of Cook and State of Illinois, in thepresence of two witnesses.

KEMPSTER B. MILLER.

Witnesses:

DAVID S. HULFISH, HARRIET IJ- SMITH.

